Broadband UHF RFID tag antenna with a pair of U slots mountable on metallic objects

A broadband ultra-high frequency radio frequency identification (UHF RFID) tag patch antenna with a pair of U slots is presented. By embedding a pair of U slots on the patch, a new resonant mode adjacent to the origin mode is excited and a broadband characteristic is achieved. The measured half-power bandwidth of the proposed antenna is 133 MHz and it covers all UHF RFID frequency bands. Measurement results show that the proposed antenna can work on metallic objects of different sizes in both North America and Europe bands.